Crust breaking apparatus



y 3, 1947- R. 1.. MOSENA ET AL 2,423,787

CRUS T BREAKING APPARATUS Filed Nov. 1. 1944 III ill. 1':

INVENTORS Rogcoe L. Maseru: George H. Traqlor Roberf L. Haislip Alvin E. Hall ATTORNEY Patented July 8, 1947 2,423,787 CRUST panama APPARATUS Roscoe Lee Mosena, George Hamilton Traylor, and Robert Lee llaislip, Maryvllle, and Alvin Earl Hall, Alcoa, Tenm, assignors to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Application November 1, 1944, Serial No. 561,434

. 3 Claims.

1 This invention relates to apparatus for breaking the frozen crust which forms on the top of molten electrolyte in aluminum-producing electrolytic cells or pots.

Breaking the crust is presently accomplished by hand tools and must be done in order to permit feeding of materials into a pot as needed and to destroy the anode efiect whenever it occurs. The task is not only extremely laborious and slow, but it is not without a sensible risk of personal danger by reason of the electrified condition of the equipment and the danger of splashing the molten electrolyte as the crust breaking operation is carried out. Moreover, in connection with reduction pots, the alumina which is to be added to the fused electrolyte or bath quite frequently is placed upon thetop of the crust for preheating, whereby the workman perforce creates a dusty atmosphere whenever he is required to break in the crust.

An object of the invention, therefore, is to provide a crust breaking apparatus incorporating a power tool by means of which a workman may rapidly and with complete safety perform a crust breaking operation.

Another object is to provide a crust breaking apparatus having a pneumatically actuated crust breaking tool mounted for bodily movement into and out of operative position together with power means for effecting movements thereof under control of the operator.

Still another object of the invention is to provide a percussively-actuated crust breaking unit movably mounted on an extendible support together with moving means for the unit effective additionally as a shock absorbing device.

A further object of the invention resides in the provision of a self-propelled machine incorporating a mechanical crust breaker and a mounting therefor affording horizontal and generally vertical movements thereof for facilitating manipulation and adjustment of the breaker relative to the crust tobe broken thereby.

A still further object is to provide a crust breaking instrumentality for a pot room of electrolytic cells which is of simple, rugged construction, eflicient in operation and eflective for eliminating the hazards of manual crust breaking as heretofore carried out. v

Other features and advantages of the invention not hereabove particularly specified will become manifest from a consideration of the following detailed description taken in conjunction with the accompanying drawings illustrating one form which the invention may take, wherein:

Fig. 1 is an end elevational view of the machine illustrated in its operating relationship to an electrolytic cell along the side of which it is adapted to be moved, the cell being shown diagrammatically partly in end elevation and partly in section.

Fig. 2 is a side elevation looking from the right side of Fig. 1, and

Fig. 3 is a control diagram.

Stated generally, the apparatus of this invention comprises a motor-driven wheeled truck or vehicle having an upright column rotatably supporting a horizontal beam or slide on the outer end of which a power tool is slidably mounted for movement downwardly into contact with the crust of the electrolytic 'pot, movement of the power tool in horizontal and vertical directions ,being effected by power actuators, and the power tool being arranged in an inclined position to permit its manipulation over the crust without danger of contacting the flexible conductors connecting the anode bus with the pot electrode.

Referring to the drawings, the electrolytic cell or pot is indicated by the numeral It), only a portion of which is shown, and the usual compound electrode is indicated by the numeral ll.

As is well known, the electrode is suspended in the fused or molten electrolyte or bath in spaced relation to the pot lining, and a frozen crust forms between the electrode and the lining at the top of the bath. This crust is indicated by the numeral l2. Along its sides and ends, the pot shell is provided with horizontal reinforcing members I3 and it is also provided with a tread plate platform It here shown as overlying the pot shell and lining.

, The truck or vehicle which carries the operating mechanism by which the crust may be broken comprises a frame or platform l5 of suitable rigid construction, a pair of rear wheels 15 mounted on axle I1 secured by brackets 18 to the underside of platform i and a pair of castormounted front wheels 19, that is, they are pivotally secured to the platform. .Cross bar 20 connects the front wheels, the point of connec tion being eccentric to the pivotal axis of each wheel. Suitable steering mechanism is provided and it comprises a vertical shaft 2| that extends centrally through a hollow vertical column 22 rigidly mounted on the upper side of the platform i5. Shaft 21 is suitably journalled in upper and lower bearings, only the lower bearing being illustrated at 23. A steering wheel 24 is keyed or otherwise suitably secured to the upper end of the shaft 2! and at its lower extremity, the shaft carries a lever 25 that is operatively connected to the cross bar 20 as by means of a slot and pin connection at 25, whereby bar 20 may be moved at will to turn the wheels I9 and steer the truck as desired. A suitable motor 21 is secured to the truck frame and it has sprocket and chain driving connection, indicated by the numeral 28, with shaft I! for driving the rear wheels iii. A multi-vane air motor actuated by compressed air has been found suitable, although other types may be employed as desired. The truck is thus self-propelled and is easily steered by the operator into position at the pot l0 and driven along the side thereof in the course of breaking in the crust [2.

The hollow column 22 rotatably supports a horizontal frame structure 30 having a shouldered depending member 3! rotatably fitted in the post 22 with the shoulder on the member bearing on the upper end of the column. Thus, a turntable support is provided for the frame structure 30 whereby it may be rotated on a vertical axis. Slidably supported by the frame structure 30 is a horizontal supporting member or slide 32. For ruggedness and ease of movement, the frame structure 30 desirably includes two tubular guide members 33 in side-by-side relation and joined adjacent their ends by cross members 34, while the slide element 32 includes two elongated bars or tubes 35 slidably extended through the tubular guide members and joined adjacent their extremities by cross bars 35 and 3?. It may be mentioned that shaft 2| is centrally disposed between the laterally spaced guide members 33.

A power actuator 38 in the form of a cylinder and piston is secured to the underside of the frame structure 30, and its piston rod 39 carries a connector 49 that has an adjustable operating connection with the slide 32. The connection suitably may comprise a flanged bar 4| secured to the slide as by welding and having a series of spaced holes through the flange thereof through one of which a pin or bolt 42 carried by the connector 40 may extend to complete the connection. The actuator 38 is adapted to move the slide 32 relative to the frame structure 30, and while the extent of the slide mo ement is fixed by the maximum stroke of the piston in the actuator cylinder, the extent of projection of the outer end of the slide from the vertical axis of the column 22 may be varied to suit operating conditions by adjustment of the connection between the connector 40 and the bar 4| At its outer end, the slide 32 carries a power-actuated crust breaker, indicated generally by the numeral 44, and it may be brought into desired position above the crust l2 by reason of the circular and horizontal movements afforded thereto by its sup- 4 porting slide and turntable mounting above described.

The crust breaker 44 preferably comprises a pneumatically actuated percussion hammer of well known construction consisting of a cylinder 45 containing a reciprocating piston (not shown) operating as a hammer for impartin impacting blows to the tool or bit 45 carried thereby, the unit being adapted to deliver a series of hard rapid blows to the crust i2 when the tool 46 is in contact therewith. This unit may take the form conveniently of a pneumatic paving breaker such as is available from various manufacturers of pneumatic tools. However, a wide blunt-nosed tool 48 is provided in order that the tool will not merely b driven through the crust as would be the case if a pointed cutting tool were used. The tool 45, as here shown, is provided with a flat face 41 of such area that it will not readily penetrate the crust but instead causes the crust 12 to crack andbreak off in pieces under the fracturing blows. Of course, the end of the tool may be made somewhat rounded like a peenlng hammer instead of flat, if desired. The pneumatic hammer 44 will be operated in the usual way from a supply of compressed air admitted thereto through the air inlet hose 48, the air flow being controlled as hereinafter described.

In carrying out an important object of the invention, the crust breaker 44 is mounted rigidly in an inclined position for movement bodily into and out of engagement with the crust I2. Hence, a slide mounting is provided which suitably comprise a slide member 54 having a base portion through which two spaced holes are provided, through which holes rods 5| extend. The rods 5| at their upper and lower ends are welded or otherwise suitably secured to a framework 52 rigidly secured to the outer end of the horizontal slide 32 in' a backwardly inclined position, the framework including the hereinbefore mentioned cross bar 35. Brace bars 52 are provided between the framework 52 and the horizontal slide bars 35 to insure rigidity of the former. A power cylinder 54 is mounted on the back of the framework 52 and it piston actuated rod 55 is connected to the slide member 50 for moving it up and down on the rods 5|. Slide member 50 is provided with spaced upstanding side plates 55 between which the breaker unit 44 is disposed and the side plates are adapted to be drawn into tight clamping engagement with the breaker unit by means of clamping bolts 51 extending therebetween. It will be seen that this mounting of the crust breaker reduces head room requirements to a minimum and assures stability during manipulation or adjustment of the unit over the crust into a desired position, that by operation of the slide 50 it is bodily raised or lowered, and that the tip of the tool 45 always describes the largest are when the slide 32 is rotated on its vertical supporting axis. Cushioning springs 58 may be provided at the opposite ends of the rods 5| "for engagement by the slide member 5!! whenever it is moved to the extreme ends of the rods.

By means of the air cylinder 54, the tool 45 of the breaker unit 44 is forced against the crust l2 firmly, yet at the same time vibratory forces generated by the hammer in operation are largely absorbed in the air cylinder instead of being transmitted throughout the whole structure. Hence, the air cylinder 54 function as a vibration damper or absorbing device to reduce the vibratory forces on both the machine and the it is quickly moved and with less power. The

slide mounting of the hammer device 44 in inclined position enables it to be manipulated over the crust l2 to points close to the electrode ll without coming into contact with electrically charged portions of the anode circuit, which, of course, gives equal protection against mechanical damage to i the equipment through collisions. The protection against electrical and mechanical hazards is enhanced by the use of rubber tires on the truck wheels and by the provision of a bumper member 60 of suitable insulating material, such as wood, along the side of the truck frame II, which insulates the truck from the pot. Normally the truck will be positioned with its bumper 60 in contact with an exterior pot rail l3 with the slide 32 adequately extended, as shown in Fig. 1, so that the tool 46 will be operated safely between electrically charged portions oi the .pot structure during such traverse of the pot by the truck as seems desirable.

It is to be noticed in Fig. 1 that the column 22 is offset from the center of the truck and located toward the side adjacent the pot wall. This is done to reduce the stroke needed to get the hammer device into desired position over the crust, to obtain maximum extension of the horizontal slide 32 with minimum cantilever length andto givea better balance condition to the structure in operating position. With the reduced cantilever length and the absorption of recoil forces of the hammer in the aircylinder 54, as above described, lighter construction of the horizontal slide and mountings may be employed without sacrifice of adequate strength.

Compressed air may be supplied from a suitable, source and conducted through a flexible hose line 6| to a pipe swivel 62 connected to the lower end of shaft 2| which is made hollow. The line 6| will be long enough at least to enable the truck to traverse the length of the pot. A second pipe swivel is connected to the upper end of shaft 2| from which the air is piped to the inlets of a pair of 4-way control valves 64 and 65 that are mounted on the steering wheel 24 and a direct air connection is also provided through hose G6 to a throttle valve 61 mounted on the wheel 24. Through hose 66, throttle valve 61 is connected to a reversing valve 68 for the air motor 21, valve 68 being adapted for foot operation by the operator to control the direction of truck travel and valve 61 being operated by hand to control the speed of truck travel in either direction.

Valve 65, as more clearly seen in Fig. 3, is connected through pipes 10 and 1| to opposite ends of air cylinder 38 and by operation of valve handle 12 retraction or advancement of the horizontal slide 32 effected. Control valve 84 is connected through flexible hose 13 to the lower end of cylinder 54 to admit air pressure for moving the slide 50 and pneumatic hammer 44 into uppermost position. The heretofore mentioned air inlet hose 48 is connected to the upper end of cylinder 54 through suitable piping including a T 14 to which a flexibl hose I5 from valve 64 is connected. Hence. it will be seen that the hammer unit 44 and cylinder 54 are connected in parallel so that upon operation of the valve 64 to admit air pressure to th line lithe slide 50 and the hammer 44 are moved downwardly to force the tool 46 firmly against the crust and simultaneously the hammering action is initiated. Reversal of valve 64 terminates the hammering action and produces elevation of the hammer unit.

Within the scope of the invention herein disclosed, the advantages and features of the invention may be obtained by various modifications and substitutions of equivalent elements and constructions without departing from the spirit vof the invention as deflned in appended claims.

What is claimed is:

1. Apparatus for breaking the crust in a. metalproducing electrolytic cell containing a suspended electrode comprising a truck movable along the cell, a vertical support rotatably mounted on said truck, an elongated supporting member slidably mounted on said vertical support in a plane above the top of said cell for movement toward said electrode in circular and radial directions, a power actuator for moving said supporting member relative to said vertical support, a pneumatic hammer slidably mounted on the -outer end of said supporting member in an inclined position and having atool on its lower end for engaging the crust in said cell, pneumatic piston and cylinder means for raising and lowering said hammer and tool with respect to said cell, and control means for said hammer and said piston and cylinder means effective to initiate operation of said hammer' simultaneously with downward movement thereof and to discontinue operation of the hammer upon upward movement thereof.

2. A machine for breaking the crust in a metalproducing electrolytic cell containing a suspended electrode, comprising a power driven.

truck progressively movable along a wall of said cell, means on one side of said truck for electrically insulating the same from said cell during said movement therealong, an elongated support rotatably mounted on said truck in a plane above the top of said cell for rotation about a vertical axis towards saidelectrode, an air hammer having a tool for breaking the crust in said cell, means slidably supporting said air hammer on the outer end of said support in a, backwardly inclined position so that said tool is outermost from said vertical axis, said air hammer being bodily movable upwardly and downwardly relative to the crust in said cell, a power actuator disposed rearwardly of said air hammer and operatively connected thereto for raising and lowering the same, and control means for said air hammer and said power actuator located on said truck.

3. A machine for breaking the crust in a metalproducing electrolytic cell containing a suspended electrode, comprising a power driven truck movable forwardly along a wall of said cell, an insulating bumper on the truck for electrically insulating the truck from said cell during said .forward movement therealong, a vertical support rotatably mounted on said truck, a cantilever member slidably mounted on th upper end of said vertical support, means for actuating said cantilever member to extend and retract the same in any angular position thereof relative to said ing spaced side plates, an air hammer clamped between said side plates in parallelism with said REFERENCES CITED The following references are of record in the file of this patent:

Number UNITED STATES PATENTS Name Date 'hittle Jan. 17, 1928 Van Sickel Mar; 12, 1907 Tobin et al Aug. 12, 1924 Edzington Sept. 16, 1924 Leavitt Dec. 9, 1902 Bennett Dec. 29, 1908 Curtis Jan. 4. 1938 Hohmann et 9.]. ....Feb. 21, 1933 Slater Feb. 21, 1933 Feller et a1 Aug. 22, 1916 Konnerth Jan. 19, 1934 

